Solid electrolytic capacitor, stacked capacitor using the same, and fabrication method thereof

ABSTRACT

On a surface-roughened aluminum foil, an aluminum oxide film as an anodic oxide film is formed. Then, a conductive polymer layer as a solid electrolyte is formed thereon and thereafter a first metal plating layer is directly formed on the conductive polymer layer, thereby forming a cathode portion. On the other hand, a second metal plating layer is formed on another portion of the surface-roughened aluminum foil, which is not subjected to anodic oxidation or which is subjected to anodic oxidation followed by polishing or formation of an anode deposition film, to thereby form an anode portion. Third metal plating layers are formed at the anode and the cathode portions to obtain a capacitor element. A plurality of capacitor elements are stacked and bonded together by fusion after formation of the third metal plating layers. Alternatively, the capacitor elements may be bonded together by a conductive paste without the third metal layers.

This application claims priority to prior Japanese patent application JP2004-214344, the disclosure of which is incorporated herein byreference.

BACKGROUND OF THE INVENTION

This invention relates to a thin-type aluminum solid electrolyticcapacitor using a single-plate aluminum foil and, more specifically,relates to a capacitor fabrication method that directly forms a metalplating layer without a pretreatment at a cathode portion and-then formsa metal plating layer at an anode portion to thereby realize lowimpedance characteristics at high frequencies and achieve an increase incapacity with stacked layers.

In recent years, following miniaturization, speed-up, and digitizationof electronic devices, there has been a strong demand for small-size,large-capacity, and low-impedance capacitors having excellenthigh-frequency characteristics also in the field of capacitors.

Capacitors that are used in a high frequency region have conventionallybeen mainly multilayer ceramic capacitors which, however, cannot satisfyneed for reduction in size, increase in capacity, and reduction inimpedance.

As large-capacity capacitors, there are electrolytic capacitors such asconventional aluminum electrolytic capacitors and tantalum solidelectrolytic capacitors. Liquid or solid electrolyte used in thosecapacitors, for example, manganese dioxide, has a high resistivity valueof 1 Ω·cm to 100 Ω·cm and therefore it has been difficult to obtain acapacitor having a sufficiently low impedance in a high frequencyregion.

In recent years, however, there have been developed solid electrolyticcapacitors using a conductive polymer compound such as polypyrrole orpolythiophen as solid electrolyte. As compared with the conventionalsolid electrolyte in the form of a metal oxide semiconductor such asmanganese dioxide, the solid electrolyte in the form of the conductivepolymer compound has a lower resistivity value of 0.01 Ω·cm to 0.1 Ω·cmwhile a resistivity value (ρ) of a used electrolyte is inverselyproportional to a frequency. Therefore, the solid electrolytic capacitorusing the conductive polymer compound having the small resistivity valueas the solid electrolyte is widely used because the impedance value in ahigh frequency region can be suppressed to a lower value.

As one example of an aluminum solid electrolytic capacitor using aconductive polymer compound as a solid electrolyte, a flat-plate elementstructure will be described. An anodic oxide film layer is formed on thesurface of a belt-shaped aluminum foil surface-roughened by etching orthe like and an insulating resin body is formed at a predeterminedportion for dividing into an anode portion and a cathode portion.Thereafter, a conductive polymer film is formed at a predeterminedportion and then a graphite layer and a silver paste layer are formed onthe conductive polymer film in the order named, thereby forming thecathode portion. Thereafter, this element cathode portion and anexternal cathode terminal are connected together by the use of silverpaste. Since the anode portion divided by the insulating resin body isin the form of the aluminum foil which is unsolderable, a solderablemetal plate is electrically connected thereto by ultrasonic welding,electric resistance welding, laser welding, or the like.

The foregoing silver paste layer formed on the conductive polymer filmcontains epoxy resin, phenol resin, or the like for providing curing andadhesive properties. As a result, there is a disadvantage in that theconductivity of the silver paste layer decreases to 1/10 to 1/100 ofthat of pure silver. Further, as described above, since the aluminumfoil at the anode portion is unsolderable, it is necessary toelectrically connect a solderable metal of a different kind by theforegoing method or the like.

Therefore, the process is complicated and, in order to achieve reductionin impedance and reduction in thickness, a totally new method inventionis necessary in terms of the silver paste layer, the connection methodfor the metal of the different kind connected to the anode portion, andthe like.

Further, in order to achieve a small-size, large-capacity, andlow-impedance capacitor which is mounted on a board with a limited floorarea, a stacked structure is required as described in JapaneseUnexamined Patent Application Publication (JP-A) 2001-358039. However,it has become difficult to achieve reduction in impedance by the use ofthe conventional silver paste or metal plate due to the influence ofreduction in thickness and conductivity.

Recently, as described in Japanese Unexamined Patent ApplicationPublication (JP-A) 2004-87872, there are a method of implementing metalplating after applying graphite onto a conductive polymer film at acathode portion and a method of implementing metal plating after forminga deposition film of noble metal on a conductive polymer film at acathode portion. However, these methods each also generate aninterfacial resistance in a pretreatment at the cathode portion,increase the thickness of a capacitor, and require more process stepsand cost.

SUMMARY OF THE INVENTION

It is therefore an object of this invention to provide a solidelectrolytic capacitor requiring only a small space while having a largecapacity and a low impedance.

It is another object of this invention to provide a stacked capacitorusing solid electrolytic capacitors each requiring only a small spacewhile having a large capacity and a low impedance.

It is still another object of this invention to provide a fabricationmethod of such a stacked capacitor.

According to one aspect of the present invention, there is provided asolid electrolytic capacitor which comprises an anodic oxide film formedon a first predetermined portion or an entire surface containing thefirst predetermined surface of a surface-roughened aluminum base body, asolid electrolyte in the form of a conductive polymer film formed at thefirst predetermined portion on the anodic oxide film, a cathode portionhaving a first metal plating layer formed on the conductive polymerfilm, an anode terminal portion having a second metal plating layerformed in the order named at a second predetermined portion other thanthe predetermined portion of the surface of the aluminum base body, andthird metal plating layers respectively formed on the first metalplating layer and the second metal plating layer that are respectivelyformed at the cathode portion and the anode terminal portion.

According to another aspect of the present invention, there is provideda stacked solid electrolytic capacitor formed by stacking a plurality ofsolid electrolytic capacitors each is above-described. In the aspect ofthe present invention, the plurality of solid electrolytic capacitorsare joined together by fusing an alloy layer of each of the third metalplating layers.

According to still another aspect of the present invention, there is astacked capacitor in the form of a plurality of solid electrolyticcapacitors stacked together. Each of the plurality of solid electrolyticcapacitors comprises an anodic oxide film formed on a predeterminedportion or an entire surface containing the predetermined portion of asurface-roughened aluminum base body, a solid electrolyte in the form ofa conductive polymer film formed at a predetermined portion on theanodic oxide film, a cathode portion having a first metal plating layerformed on the conductive polymer film, an anode terminal portion havinga second metal plating layer formed in the order named at a secondpredetermined portion other than the first predetermined portion of thealuminum base body, and conductor layers respectively formed on thefirst metal plating layer and the second metal plating layer that arerespectively formed at the cathode portion and the anode terminalportion. In the aspect of the present invention, the plurality of solidelectrolytic capacitors are joined together by the use of conductivepaste as the conductor layers after formation of the first metal platinglayer and the second metal plating layer.

According to yet another aspect of the present invention, there isprovided a method of fabricating a stacked capacitor by stackingtogether a plurality of the solid electrolytic capacitors abovedescribed. The method comprises the steps of cutting an aluminumchemical conversion foil into a predetermined shape to form an aluminumframe, forming a plurality of solid electrolytic capacitor elements onthe frame,

stacking a plurality of the frames at predetermined positions, fixingthe stacked plurality of frames by heating to fuse copper-tin alloyplating layers, and cutting the fixed plurality of frames atpredetermined portions, thereby forming the stacked capacitor.

According to a further aspect of the present invention, there isprovided a method of fabricating a stacked capacitor in the form of aplurality of solid electrolytic capacitors stacked together. The methodcomprises the steps of cutting an aluminum chemical conversion foil intoa predetermined shape to form an aluminum frame, forming an anodic oxidefilm on a first predetermined portion or an enter surface containing ofthe first predetermined portion of the aluminum frame, forming a solidelectrolyte in the form of a conductive polymer film at the firstpredetermined portion on the anodic oxide film, forming a cathodeportion to have a first metal plating layer on the conductive polymerfilm, forming an anode terminal portion to have a second metal platinglayer at a second predetermined portion other than the firstpredetermined portion of the aluminum frame, forming conductor layersrespectively formed on the first metal plating layer and the secondmetal plating layer that are respectively formed at the cathode portionand the anode terminal portion, stacking a plurality of the frames atpredetermined positions after formation of the first metal plating layerand the second metal plating layer, joining together the stackedplurality of frames by the use of conductive paste as the conductorlayers, and cutting the joined plurality of frames at a predeterminedparts to form each of the plurality of solid electrolytic capacitors,thereby forming the stacked capacitor.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a sectional view of a conventional aluminum solid electrolyticcapacitor;

FIG. 2 is a sectional view of a conventional stacked capacitor;

FIG. 3 is a sectional view showing components of an aluminum solidelectrolytic capacitor applied with copper plating and copper-tin alloyplating according to a first embodiment of this invention;

FIG. 4 is a sectional view showing components of an aluminum solidelectrolytic capacitor applied with nickel plating, copper plating, andcopper-tin alloy plating according to a second embodiment of thisinvention;

FIG. 5 is a sectional view showing a basic structure of an element(basic element) having an aluminum metal base body, a dielectricaluminum oxide film formed thereon, and a conductive polymer layer,serving as a solid electrolyte, formed on the dielectric aluminum oxidefilm;

FIG. 6 is a sectional view of an aluminum solid electrolytic capacitoraccording to a third embodiment of this invention;

FIG. 7 is a diagram showing ESR characteristics of aluminum solidelectrolytic capacitors;

FIG. 8 is a sectional view of a stacked capacitor according to a fourthembodiment of this invention;

FIG. 9 is a sectional view of a stacked capacitor according to a fifthembodiment of this invention;

FIG. 10 is a diagram showing frequency characteristics of impedance ofstacked capacitors; and

FIGS. 11A through 11C are schematic views for use in explaining aprocess of manufacturing the stacked capacitor according to one exampleof the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In order to facilitate understanding of this invention, a conventionalsolid electrolytic capacitor and stacked capacitor will be describedwith reference to the drawings prior to describing embodiments of thisinvention.

Referring to FIG. 1, in fabrication of a conventional solid electrolyticcapacitor 103, there is obtained a chemical conversion foil composed ofa surface-roughened aluminum foil 1 having a predetermined shape and analuminum oxide film 2 formed on the surface of the aluminum foil 1 byanodic oxidation. This chemical conversion foil is cut into apredetermined shape to thereby form an aluminum frame and then aconductive polymer film is formed on the aluminum frame at portionswhere a plurality of solid electrolytic capacitor elements will beformed, thereby obtaining a basic element 20. On a conductive polymerlayer 3 in the form of the conductive polymer film of the basic element20 is formed a graphite layer 8 in the form of a carbon-deposition filmand then a conductive paste layer 9 is formed on the graphite layer 8.Further, at an anode portion, conductive metal is directly weldedthereto or a solder layer is formed after plating, thereby forming ananode terminal portion 10.

Referring to FIG. 2, a conventional stacked capacitor 108 has astructure in which a plurality of solid electrolytic capacitors 103 arestacked together and, in the illustrated example, has a five-layerstructure.

Referring to FIGS. 3 to 11C, the embodiments of this invention will bedescribed.

In FIG. 11A, there is obtained a chemical conversion foil composed of asurface-roughened aluminum foil 1 having a predetermined shape and analuminum oxide film 2 formed on the surface of the aluminum foil 1 byanodic oxidation. Herein, reference numeral “1 a” represents a punch outhole, which will be a guide for cutting along a cutting line 1 b. Thischemical conversion foil is cut into a predetermined shape to therebyform an aluminum frame and then a conductive polymer film is formed onthe aluminum frame at portions where a plurality of solid electrolyticcapacitor will be formed, thereby obtaining a basic element 20. Metalplating such as copper plating or nickel plating is directly applied toa conductive polymer layer 3 in the form of the conductive polymer filmof the basic element 20 to thereby form a first metal plating layer (I).Then, after forming a deposition layer 4 on the anodic oxide film 2 orafter polishing this anodic oxide film 2, a second metal plating layer(II) composed of a single layer or a plurality of layers is formed atthis anode portion. Thereafter, a third metal plating layer (III) 7formed by copper-tin alloy plating using an alloy of copper and tin isformed on the outermost surface layers. Then, as shown in FIG. 11B, apredetermined number of the frames 100 each having the foregoingstructure are stacked at predetermined positions, then fixed together byheating to fuse the copper-tin alloy plating layers, then cut atpredetermined portions which are represented by the cutting lines 1 bparallel to each other, thereby producing stacked solid electrolyticcapacitors (each being a stacked capacitor 105 or 106) shown in FIG.11C.

Specifically, after forming the conductive polymer layer 3 at thealuminum frame cathode portion, the anode portion is subjected tomasking by the use of a resist 11 or the like. Thereafter, the aluminumframe with the conductive polymer layer 3 and the masked anode portionis immersed in a copper sulfate electroplating liquid or a nickelelectroplating liquid manufactured by, for example, Uyemura & Co., Ltd.Herein, the copper sulfate electroplating liquid is an aqueous solutioncontaining sulfuric acid, copper sulfate, hydrochloric acid, and anadditive (THRU-CUP EPL), while the nickel electroplating liquid is anaqueous solution containing nickel sulfate, nickel chloride, and boricacid.

Then, using the aluminum frame as a cathode and a copper or nickel plateas an anode, a voltage of 0.1V to 10V is applied for 1 to 120 minutesand, after cleaning and drying to form a metal plating film, theseprocesses are repeated for 1 to 10 cycles until the thickness of thefilm reaches 1 to 20 μm for blocking oxygen. Subsequently, the framewith the metal plating film is immersed in a lead-free copper-tin alloyplating liquid manufactured by, for example, Uyemura & Co., Ltd. Herein,the lead-free copper-tin alloy plating liquid is an aqueous solutioncontaining Sn²⁺, Cu²⁺, and free acid. Then, using the aluminum frame asa cathode and a tin plate as an anode, a voltage of 0.1V to 20V isapplied for 1 to 60 minutes to thereby obtain a copper-tin alloy platingfilm.

As compared with the conventional graphite or silver paste having aconductivity of 1.0×10² to 10⁴S/cm or 1.54×10⁴S/cm, each of theforegoing copper plating film and copper-tin alloy plating film at thecathode portion has a higher conductivity of 0.9 to 5.6×10⁵S/cm.Therefore, in terms of conductivity σ=1/ρ (resistivity) and R=ρ·1/S, itis considered that lower impedance characteristics can be obtained. Inaddition, the copper plating film and copper-tin alloy plating film canbe formed thinner than a silver paste film.

Description will be given below about a method of Cu plating, at theanode portion, onto the aluminum metal base body or the dielectric oxidefilm 2 formed on the surface thereof.

After forming the foregoing copper-tin alloy plating layer at thecathode portion, the cathode portion is subjected to masking by the useof a resist 11 or the like. Then, noble metal such as gold, platinum, orsilver, or carbon is deposited to form an anode deposition film 4 at theanode portion. Alternatively, it may be arranged that, in the process offorming the anodic oxide film 2 on the aluminum foil which issurface-roughened by etching or the like, masking is partially appliedby the use of the resist 11 so as not to form the oxide film 2 at theanode portion, that the anodic oxide film 2 is polished at the anodeportion, or that, as a zincate process, after masking the cathodeportion, the anode portion formed with the oxide film 2 is immersed in astrong acid such as nitric acid or sulfuric acid for 10 to 300 seconds,then well washed and, after immersing it in a zincate treatment liquidfor 10 to 300 seconds, it is well washed-and-dried to thereby remove theoxide film. In the zincate process, immersion, washing, and drying maybe repeated several times to achieve a better effect. Then, the anodeportion where the anode deposition film 4 is formed or the oxide film 2is not formed is immersed in the foregoing copper sulfate electroplatingliquid or nickel electroplating liquid to form a second metal platinglayer (II) by copper or nickel plating like at the cathode portion.Further, a copper-tin alloy plating layer is also formed like at thecathode portion.

There is another method wherein the first metal plating layer (I) at thecathode portion is made of copper or nickel, or obtained by firstforming a nickel film and then forming a copper film thereon, the secondmetal plating layer (II) at the anode portion is made of copper ornickel, or obtained by first forming a nickel film and then forming acopper film thereon and, after forming the second metal plating layer(II), third metal plating layers (III) of copper-tin alloy plating areformed simultaneously at the cathode and anode portions.

After the formation of the third metal plating layers (III), the frameis cut into capacitor elements of a predetermined size, then theelements are stacked together, and then the copper-tin alloy platinglayers at the anode and cathode portions are melted and welded togetherat 230° C. to 350° C., thereby forming an intended large-capacitylow-impedance stacked aluminum electrolytic capacitor (stacked capacitor105 or 106).

There is also a method of forming a stacked aluminum electrolyticcapacitor by bonding the capacitor elements by the use of conductivepaste 9 after the formation of the third metal plating layers (III). Thealuminum solid electrolytic capacitor obtained by such a method is acapacitor featured by improvement in contact with solder and reductionin thickness which have been the objects to be achieved.

As described above, according to this invention, since the metal platinglayer is directly provided on the conductive polymer film at the cathodeportion of the solid electrolytic capacitor element, there is an effectof reduction in thickness and reduction in impedance as extractionelectrodes having a high conductivity. Further, by providing the copperplating or the copper-tin alloy plating on the metal plating layer, thestacked solid electrolytic capacitor can be formed using only the metalshaving high conductivities. This makes it possible to provide analuminum solid electrolytic capacitor requiring only a small space whilehaving a large capacity and a low impedance.

Hereinbelow, specific examples of this invention will be described indetail with reference to the drawings.

That is, each example of this invention shows an element structurechange from FIG. 5 to FIG. 3 or FIG. 4 and a forming method thereof.

Hereinbelow, fabrication examples where copper plating, nickel plating,and copper-tin alloy plating are used for the first, second, and thirdmetal plating layers (I), (II), and (III) will be described withreference to the drawings.

EXAMPLE 1

In a basic element 20 shown in FIG. 5, a conductive polymer layer 3 inthe form of a conductive polymer film is formed on a dielectric oxidefilm 2 of an aluminum foil 1 formed with the dielectric oxide film 2 bysurface roughening. Symbol 11 denotes a resist for dividing into ananode portion and a cathode portion. In the basic element 20 after theformation of the conductive polymer film, a copper plating layer wasdirectly formed as a first metal plating layer (I) 5 a on the cathodeportion conductive polymer layer 3 as shown in FIG. 3. Alternatively,after forming a graphite layer on the cathode portion conductive polymerlayer 3, a copper plating layer was formed as a first metal platinglayer (I) 5 a. Then, the respective samples were each applied, as apretreatment for anode portion copper plating, with a zincate treatment,with gold deposition, platinum deposition, or carbon deposition to forman anode deposition film 4, with masking so as not to form the oxidefilm at the anode portion, or with polishing of the oxide film at theanode portion, and then the copper plating was applied to each sample atthe same application voltage for the same voltage application time tothereby form a second metal plating layer (II) 6 a. Thereafter, withrespect to each of aluminum solid electrolytic capacitors applied withplating of a copper-tin alloy having a melting point of about 230° C. to350° C., the capacity at 120 Hz, the ESR at 1 kHz, and the ESR at 100kHz were measured. The results are shown in Tables 1 and 2 given below.

TABLE 1 Anode Pretreatment and Characteristics in Case of Direct CopperPlating on Polypyrrole at Cathode Portion Direct Cu Plating on PPy FilmZi Treatment Under Plating Au Pt C Oxide Film Masking Anode OxidePre-treatment Deposition Deposition Deposition Removal No Oxide FilmFilm Polishing 120 Hz 25.5 25.3 26.2 24.9 25.1 25.0 Cap (μF)  1 kHz 120102 107 125 95 97 ESR (mΩ) 100 kHz 6.8 5.9 4.2 7.2 6.0 6.2 ESR (mΩ)

TABLE 2 Anode Pretreatment and Characteristics in Case of Copper Platingafter Graphite Application at Cathode Portion Cu Plating after GraphiteApplication Zi Masking Anode Conventional Under Plating Au Pt CTreatment Oxide Oxide Film Oxide Film Ag Paste & Pre-treatmentDeposition Deposition Deposition Film Removal Removal Polishing AnodeTerminal 120 Hz 25.5 26.3 25.5 26 25.5 25.3 23.6 Cap (μF)  1 kHz 97 96112 109 90 93 254 ESR (mΩ) 100 kHz 14.8 14.7 17.2 15.6 14.5 15 18.0 ESR(mΩ)

EXAMPLE 2

As shown in FIG. 3, a first metal plating layer (I) 5 a on polypyrroleand a second metal plating layer (II) 6 a on a metal deposition layer 4were formed by copper plating, respectively, according to the foregoingcopper plating method and third metal plating layers (III) 7 were eachformed by a copper-tin alloy plating layer, thereby preparing a solidelectrolytic capacitor 101.

As shown in FIG. 4, a nickel plating layer was formed as a first layer 5a of a first metal plating layer (I) on a basic element 20 and a copperplating layer was formed as a second layer 5 b on the first layer 5 a,while, likewise, a nickel plating layer was formed as a first layer 6 aof a second metal plating layer (II) and a copper plating layer wasformed as a second layer 6 b on the first layer 6 a, and third metalplating layers (III) 7 were each formed by a copper-tin alloy platinglayer, thereby preparing a solid electrolytic capacitor 102.

As shown in FIG. 6, a graphite layer 8 was formed on a polypyrrole layer3, a copper plating layer was formed thereon as a first metal platinglayer (I) 5 a, a copper plating layer was formed as a second metalplating layer (II) 6 a on an anode deposition film 4 at the anodeportion, and third metal plating layers (III) 7 were each formed by acopper-tin alloy plating layer, thereby preparing a solid electrolyticcapacitor 104.

As shown in FIG. 1, a conductive polymer layer 3 at the cathode portionwas made of polypyrrole and an external extraction electrode was formedby a graphite layer 8 and a conductive paste layer 9 made of Ag paste,thereby preparing a solid electrolytic capacitor element 103.

With respect to the elements 101, 102, 103, and 104, the frequencycharacteristics of ESR were measured, respectively. The results areshown in FIG. 7.

EXAMPLE 3

After forming a plurality of solid electrolytic capacitors 101 on theframes shown in FIG. 8, the frames were stacked together and thencopper-tin alloy plating layers 7 as third metal plating layers (III) 7were heated and melted at 230° C. to 350° C. so as to be bondedtogether, thereby producing five-layer stacked capacitors 105 of thisinvention.

Further, the frames shown in FIG. 9 were stacked together atpredetermined positions, then solid electrolytic capacitors 107 werejoined together by the use of conductive paste and then cut atpredetermined portions, thereby producing five-layer stacked capacitors106.

For comparison, there was produced a conventional five-layer stackedcapacitor 108 using graphite, silver paste, and terminal plates as shownin FIG. 2.

FIG. 10 shows frequency-impedance characteristics of the stackedcapacitors 105, 106, and 108, respectively.

As shown in FIG. 10, it is understood that the impedance of the stackedcapacitor 105 of this invention is lower than that of the stackedcapacitor 106 of this invention over the whole frequency range, whilethe impedance of the stacked capacitor 106 is lower than that of theconventional stacked capacitor 108 over the whole frequency range.

As described above, the aluminum solid electrolytic capacitor and thestacked capacitor according to this invention are each optimal as acapacitor for use in a high-frequency electronic device.

Naturally, the stacked capacitor of this invention can be used in, forexample, a decoupling circuit for connection to a power supply of a CPUof a PC, as a line element that uses the anodes on both sides and thecathode at the center as three terminals.

Although the description has been given of the embodiments of thisinvention, it is readily understood that this invention is not limitedto those embodiments and that various changes can be made within therange of spirit and scope of this invention.

1. A solid electrolytic capacitor comprising: an anodic oxide filmformed on one of: (i) a first predetermined portion of a surface of asurface-roughened aluminum base body, and (ii) an entire surface,containing the first predetermined portion, of the aluminum base body; asolid electrolyte, comprising a conductive polymer film, formed at thefirst predetermined portion on the anodic oxide film; a cathode portionincluding a first metal plating layer formed on the conductive polymerfilm; an anode terminal portion including a second metal plating layerformed at a second predetermined portion other than the firstpredetermined portion of the surface of the aluminum base body; andthird metal plating layers respectively formed on the first metalplating-layer and the second metal plating layer that are respectivelyformed at the cathode portion and the anode terminal portion; whereinthe second predetermined portion comprises a surface of a vapordeposited film formed on the anodic oxide film, and the deposited filmcomprises an inorganic conductive deposition film.
 2. A solidelectrolytic capacitor according to claim 1 wherein each of the thirdmetal plating layers comprises a copper-tin alloy layer.
 3. A solidelectrolytic capacitor according to claim 1, wherein the inorganicconductive deposition film is one of: (i) a carbon deposition film, and(ii) a metal deposition film made of one of platinum and gold.
 4. Asolid electrolytic capacitor according to claim 1 wherein each of thefirst metal plating layer and the second metal plating layer comprisesone of: (i) a two-layer structure of a nickel layer and a copper layer,and (ii) a single-layer structure of one of a copper layer and a nickellayer.
 5. A solid electrolytic capacitor according to claim 1 whereineach of the third metal plating layers comprises an alloy layer having amelting point of 230° C. to 350° C.
 6. A solid electrolytic capacitoraccording to claim 1 wherein the first metal plating layer comprises agraphite layer and a copper paste layer.
 7. A stacked solid electrolyticcapacitor comprising: a plurality of the solid electrolytic capacitorsaccording to claim 1 wherein each of the third metal plating layerscomprises an alloy layer; wherein the plurality of solid electrolyticcapacitors are stacked and joined together by fusing the alloy layers ofthe third metal plating layers of adjacent ones of the stacked solidelectrolytic capacitors.
 8. A stacked solid electrolytic capacitoraccording to claim 7 wherein the first metal plating layer of each ofthe solid electrolytic capacitors comprises a copper paste layer formedon a graphite layer, wherein the graphite layer is formed on theconductive polymer film, and the copper paste layer and the graphiteform a two-layer structure.
 9. A solid electrolytic capacitor accordingto claim 1 wherein the capacitor is used as a line element that ismounted on a board.
 10. A stacked capacitor comprising: a plurality ofsolid electrolytic capacitors stacked together; wherein each of theplurality of solid electrolytic capacitors comprises: an anodic oxidefilm formed on one of: (i) a first predetermined portion of a surface ofa surface-roughened aluminum base body, and (ii) an entire surface,containing the first predetermined portion, of the aluminum base body; asolid electrolyte, comprising a conductive polymer film, formed at thefirst predetermined portion on the anodic oxide film; a cathode portionincluding a first metal plating layer formed on the conductive polymerfilm; an anode terminal portion including a second metal plating layerformed at a second predetermined portion other than the firstpredetermined portion of the surface of the aluminum base body; andconductor layers respectively formed on the first metal plating-layerand the second metal plating layer that are respectively formed at thecathode portion and the anode terminal portion; wherein the secondpredetermined portion comprises a surface of a vapor deposited filmformed on the anodic oxide film, and the deposited film comprises aninorganic conductive deposition film; and wherein the conductive layerscomprise conductive paste, and the plurality of solid electrolyticcapacitors are joined together by the conductive paste.